When learning about these tools, I (naively) thought that mapping about the business space could be front loaded by doing it only once and refering to those diagrams for each project within a single business unit. However, I am finding that each situation is calling for it's own set of diagrams to properly communicate what's going on. I find that I am dealing with the same objects, but the relationships change.
My first thought to these different situations was that these were sort of disposable* diagrams as they only pertain to a very narrow scope within the business, but I quickly retracted that thought once I found myself scrambling to find the same ER diagram I disposed 3 months ago in a completely different situation. So now I am getting a sence that they are not disposable and should be kept, but I want to avoid just a stack of seemingly contradicting UML and ER diagrams so that someone behind me can make sense of it all. Any suggestions?